While the crabs sound great, I think I definitely have my answer. In the end, I wasn't really even considering doing this, but as has been mentioned several times in this thread, I'm at the point where I can't walk past anything without thinking about using it in my setup (I never would have thought that rubbermaid coolers would look so appealing...).
The build-quality issue is really what would keep me from doing this. While losing a bunch of boil water for your crabs is kinda crappy, losing 5 gals of precious wort after hand-grinding 12lb of grain would simply break my heart. I'm glad this post sparked a bit of interesting discussion though. I'd certainly be interested to hear about other interesting boil-kettle ideas that have worked. Another thought I'd considered was using one of those antique, metal milk cans. I think those too might be galvanized though, and likely have a seam at the bottom.
